1. Field of the Invention
The present invention generally relates to a fixing device and more particularly, to a contact and spacing mechanism of a pressure roller in a toner image fixing device for use, for example, in an electrophotographic copying apparatus, arranged to pass a toner image carrying support material, such as copy paper or the like, between a fixing roller and the pressure roller so as to fix the toner image onto the support material.
2. Description of the Prior Art
Conventionally, for a contact and spacing mechanism of a pressure roller for the toner image fixing device of the above described type, there have been employed arrangements which employ a clutch or solenoid or a combination of both for practical applications.
The known contact and spacing mechanisms of the pressure roller as described above, however, have problems in that, in the case where a driving power source is turned off during pressure contact of the pressure roller with the fixing roller, inertia of motor or weight of the pressure roller must be relied upon for the releasing of the contact force, and thus, an excessively large torque tends to be applied to bearing portions, with a consequent unstable functioning of the mechanism on the whole.